JP2000507736A - Light-recirculating back-coupled lighting system - Google Patents

Abstract

The light output of a back-coupled illumination system is improved by recycling reflected and misdirected light rays. A reflector at the light source and an array of microprisms having reflective elements therebetween efficiently redirect errant light rays to increase the total available light output and improve efficiency. Both specular and diffuse reflective materials may be used in combination to enhance light output.

Description

DETAILED DESCRIPTION OF THE INVENTION Background of the Invention Light Recirculating Back-Coupled Lighting Devices Background of the Invention Currently available lighting devices for direct lighting and other applications are designed to absorb or dissipate light in unwanted directions. Suffering light loss. The available power of the light source increases if the rays lost due to absorption and dissipation in unwanted directions are captured and used. A lighting device that accomplishes this would be eager. The present invention accomplishes this and other objects of redirecting and recycling light that would otherwise be lost. BRIEF DESCRIPTION OF THE DRAWINGS The invention and further advantages will be more fully understood with reference to the following detailed description of the invention and the accompanying drawings. FIG. 1 is a schematic block diagram of a lighting device; FIG. 2 is a schematic cross-sectional view of an embodiment of the lighting device; FIGS. 3 to 5 are schematic cross-sectional views of an alternative example of a reflector for a light source; 7 to 12 are perspective views of an alternative microprism; FIG. 13 is a perspective view of a linear array of microprisms; 15 is a schematic cross-sectional view of an embodiment; FIG. 15 is a schematic cross-sectional view of an arrangement of a microprism and a lens, which is eccentric with respect to the geometric center of the microprism; FIGS. FIG. 24 is a top view of a mask used in the illumination device of FIG. 18; FIGS. 25 to 28 are perspective views of an alternative illumination device; FIGS. 29 to 32 are additional alternative illumination devices. FIG. 33 is a schematic sectional view of FIG. Ryakkai sectional view of the device; and FIG. 34 and FIG. 35 are examples of commercial semicylindrical reflector and ceiling-embedded spotlights incorporated in the lighting devices described herein. DETAILED DESCRIPTION OF THE INVENTION The present invention comprises (a) a light source, (b) a light directing assembly in close proximity to the light source, and (i) at least one microprism, wherein the microprism is a light source. An input surface permitting light to radiate from the input surface, an output surface remote from and parallel to the input surface, and disposed between and adjacent to the input surface and the output surface, forming an obtuse angle with the input surface; And (ii) at least one blocking means for blocking an optical path through the side wall, the at least one side wall being arranged to be effective for total internal reflection of light rays received by the input surface. A conceptual depiction of the present invention is the lighting device 10 in the simplified block diagram of FIG. The lighting device 10 is divided into two sub-assemblies, a lighting assembly 12 and a light directing assembly 14. Arrow 20 indicates the direction of the light wave from illumination source 12 through light directing assembly 14 to a pointing object (not shown). It should be appreciated that this drawing is merely a schematic representation of the structure and is not intended to imply actual or relative dimensions of the elements of the device or its physical arrangement. A specific embodiment 100 of the lighting device is shown in FIG. The device 100 has a lighting assembly 110 and a light directing assembly 120 of at least one microprism 122 optionally supported on one side of a base wall 124. The light directing assembly 120 optionally includes a lens or lens array on the other side of the base wall 124 to control the angular distribution of light output of the lighting device 100. Lighting Device Assembly The lighting device assembly 110 has a light source 112, which is suitable for use, such as an incandescent lamp, a light emitting diode (LED), a metal or halogen high intensity discharge lamp, a fluorescent lamp, or the like. Other light sources may be used. In a preferred embodiment, the illuminator assembly 110 has a reflector 150 located behind or around the light source 112, ie, spaced from the light directing assembly 120. The reflector 150 reflects light propagating away from the light directing assembly 120 back to the microprism 122. Reflector 150 can be made from a diverging or highly reflective metal, such as polished aluminum or white paint, although in other applications a highly reflective material is preferred. The metal selected for the reflector has a reflectivity in the range of about 75% to 90%, preferably greater than 90%. Reflectance can be measured with several commercially available instruments, such as a Macbeth # 7100 spectrophotometer, New Windsor, N, Y, or Perkin Elmer # 330 spectrophotometer, Danbury, CT. The mounting location of the reflector with respect to the light source and the light directing assembly, and the distance between them, should be selected to maximize the light directed to the light directing assembly. As will be readily appreciated by those skilled in the art, the mounting locations and the distance between them can be determined by the relative size of the light source and reflector, and the design of the reflector. Depending on the physical dimensions of the light source, the distance between the light source and the reflector is typically one to two times the diameter of the light source. The distance between the light source and the light directing assembly is typically one to two times the diameter of the light source. For example, if a T-5 fluorescent lamp is used as a light source having a diameter of about 1/8 inch, the distance between the fluorescent lamp and the reflector, as well as the fluorescent lamp and the light directing assembly, The distance between them is typically in the range of about 0.688 inches to 1.375 inches. The reflector 159 of FIG. 2 is parabolic in shape, but may be of other shapes as will be apparent to those skilled in the art. For example, as shown in FIG. 3, the reflector 230 is rectangular in shape and has two side walls 232 and a base 234. To accommodate the geometry and spectral pattern of the light source 112, the angle of the side wall 232 with respect to the base 234 can be adjusted to form a right, acute, or obtuse angle. Other shapes of reflectors, such as pointed, faceted, or fan shaped reflectors, as shown in FIGS. 4 and 5, respectively, can also be used. In addition, instead of forming reflector 150 from a continuous piece of material, it may be divided into two or more parts. Instead of artificial light sources of the type described above, natural or ambient light, such as direct sunlight, may be used. In that case, the lighting device assembly 110 does not require a reflector. Light directing assembly The microprism 122 shown in FIG. 2 is a polyhedron having four inclined sides. These particular microprism structures are described in U.S. Pat. No. 5, issued to Beeson et al. On Mar. 7, 1995 to "Backlighting Device Using an Array of Microprisms". No. 396,350. This US patent is incorporated herein by reference. As shown in FIGS. 6 and 7, each microprism 122 has an input surface 132, an output surface 134, and opposing side walls 136, each of which has an input surface 132 and an output surface 134, respectively. Adjacent. The junction between the side wall 136 and the input surface 132 defines an obtuse tilt angle α. FIG. 13 shows an array 220 of linear microprisms 210 supported on a base wall 220. Other shapes can be used instead of the microprism geometry of FIG. FIGS. 8 to 12 show other microprisms: conical (FIG. 8), polyhedral (FIG. 9), polyhedronal curvilinear (FIGS. 10 and 11), and curves. This is a microprism (FIG. 12). The above examples are for illustration only, and other geometric shapes may be used, as will be readily apparent to those skilled in the art. Furthermore, the cross section of the microprism 122 may be asymmetric (eg, rectangular). The size of the microprism 122 affects the light output distribution of the light directing assembly 120. In particular, the area of the input surface 132, the height of the side wall surface 136, and the angle of inclination α of the side wall 136 are adjusted together to change the path of light through the microprism 122. A narrow output angle distribution is achieved by reducing the surface area of the input surface 132, while increasing the height of the sidewalls 136 and minimizing the obtuse tilt angle α. Alternatively, the output angle distribution can be increased by decreasing the height of the sidewalls 136 and increasing the surface area of the input surface 132 while increasing the magnitude of the obtuse angle of inclination α. Where the base wall 124 is used, additional control of the angular dispersion of the output of the lighting device 100 can be achieved by varying the thickness of the wall 124. For a given positive radius of curvature of the lens 142, increasing the thickness of the base wall 124 increases the separation between the microprism 122 and the lens array 140 and reduces the angular distribution of the output of the illumination device 100. Will increase. Although the lenses 142 shown in FIG. 2 are convex, they may be spherical concave, aspheric, cylindrical convex, cylindrical concave, or described by a particular application or readily by those skilled in the art. Other suitable shapes that come to mind can be used. Further, the lens 142 may be directly disposed on the output front 134 when the base wall 124 is not provided. Further, the lens may be a diffractive element, a refractive element, or a combination of a diffractive and a refractive element. The lighting assembly 110 and the light directing assembly of the back-coupled lighting device 100 can be utilized without a lens, as shown in the structure of FIG. Further, the axis of the lens 142 in FIG. 2 is aligned with the geometric center 126 of the microprism 122 here. If desired, lens 142 may be offset or eclipsed with respect to geometric center 126 of microprism 122, as shown in FIG. Finally, the cross-sectional dimensions of the lens can vary with respect to the cross-section of the microprism 122. The distance between the geometric center 126 of each microprism 122 and the geometric center of the lens 142 can be varied from zero to one-half the width of the output surface 134 of the microprism 122. The lens 142 may be positioned adjacent to the output surface 134 of the microprism 122 or may be positioned at a distance of up to half the distance between the input surface 132 and the output surface 134 of the microprism 122. Good. The microprisms 122 and associated structures (including an optical lens array) are described in U.S. Pat. No. 5,396,350, entitled "Illumination Device Using an Array of Microprisms," on Jun. 27, 1995. No. 5,248,468 issued to Zimmerman et al. And "Direct View Display with Array of Inclined Waveguides", issued Jan. 2, 1996 to Zimmerman et al. (Zimmerman et al) and can be made according to the methods set forth in US Pat. No. 5,481,385 and using the materials set forth in those patents. These patents are incorporated herein by reference. As shown in the referenced patents, the arrangement of microprisms and lenses is based on polycarbonate, acrylic, polystyrene, glass, transparent ceramic and "tilted photopolymerized waveguides" by Beeson et al. al) can be made from a variety of materials, including monomer mixtures, as described in US Pat. No. 5,462,700 issued Oct. 31, 1995. The heat generated from the light source should be considered when choosing the materials of construction for these structures. If desired, the lens assembly may be provided as a separate sheet laminated to the base wall of the light directing assembly, or with the light directing assembly using injection molding or other techniques readily apparent to those skilled in the art. It may be made as an integral structure. The side wall 136 of the microprism 122 of the light directing assembly 120 defines a region 128 adjacent to the side wall 136. Within light directing assembly 120 having a plurality of microprisms 122, these areas are referred to as "gap" areas. These areas 128 are provided with reflective elements. The reflective element is a highly reflective solid padding 160 shaped as shown in FIG. The solid filling 160 may be a mirror-like material or a material that scatters or diffuses light. Further, the solid filling 160 may include a material such as BaSO ₄ , TiO _2, or MgO, which has good reflectivity to visible light due to its fine structure. These materials may be used with carriers such as dry powders, paints and putties. Alternatively, a material such as Spectralon (a trademark of Labsphere, Inc.) or Teflon (a registered trademark of du Pont) may be attached to this region with a material that is stable to the environmental conditions where the lighting device will be attached. May be provided with a high degree of reflectivity. The solid filling 160 desirably has a high reflectivity, that is, a reflectivity of 90% or more, but a material having a lower reflectivity may be applicable in some cases. Materials may be desirable. Other reflective materials can also be used as reflective elements. In FIG. 16, the side wall 136 of the microprism 122 has a coating 260 of a reflective material. The coating 260 can be silver, aluminum, gold, white enamel, or any other material readily apparent to one skilled in the art. These materials are deposited by chemical vapor deposition, electron beam evaporation, sputtering, or the like. In FIG. 17, the reflective element is a reflective lining 270. The reflective lining 270 is molded integrally with the side wall 136 or attached to the side wall 136 by an adhesive or other known means. In FIG. 18, a mask 280 is used as a reflective element, and the mask 280 covers the area 128 between the microprisms 122. As shown in FIG. 24, the plan view of the mask 280 has a grating configuration having an opening 282 through which the input surface 132 of the microprism 122 can enter. The mask may be made of a mirror-like or scattering (diffuse) solid material, as described above. The reflective elements (coatings, linings and masks) in FIGS. 16-18 can be mirror-like or scattering (diffuse) and have a reflectance in the range of about 75 to 90 percent. And preferably has a reflectance of 90% or more. One example of a mirror-like material is Silver erlux ™, which will be manufactured by 3M, although other materials readily available to one of skill in the art are also available. The reflectance can be measured as described above. Different types of reflective materials can also be used in combination. As shown in FIG. 19, the side wall 136 has two reflective elements, a coating 260 and a mask 280. Reflective lining 270 and solid padding 160 are provided in area 128 of the assembly, as shown in FIG. In this embodiment, a material such as a mirror may be selected for the lining 270 and a scattering (diffuse reflection) material may be selected for the filling 160. Further, other combinations may be used. In FIG. 21, the side wall 136 has a coating 260 and a solid filling 160. A reflective lining 270 and a mask 280 are provided in region 128 of the assembly, as shown in FIG. Finally, a solid padding 160 and a mask 280 are provided in region 128, as shown in FIG. The configurations discussed so far have been linear or planar. The illumination system may be formed in a curved or spherical arrangement, as shown in FIGS. 25 and 26, respectively. Alternatively, they may be formed in other arrangements that can be easily conceived by those skilled in the art. In FIG. 25, light source 300 faces a curved array 310 of microprisms. In FIG. 26, the light source 320 is housed in a partially spherical array 330 of microprisms. In order to shape the light directing assembly in this way, it is necessary to adjust the angle of inclination of the side wall of the microprism with respect to the input surface so as to give the spherical emitter a suitable angular distribution. In addition, the spacing between the microprisms may need to be varied to be able to control the light properly. The input and output surfaces of the microprism may be flat, curved, or spherical. The light directing assembly of FIGS. 25 and 26 may be provided with a bottom wall adjacent to the output surface of the microprism, if desired. A lens may be provided in such a manner. Further, combining a plurality of flat and / or curved light directing assemblies 340 with one or more light sources 350 to form a polyhedral lighting device as shown in FIGS. 27 and 28, Irradiation in a plurality of directions may be performed. The individual microprisms of one flat assembly are shown in FIG. 27a. The intensity of light entering the light directing assembly 120 can be controlled by inserting an optical element 400 between the light source 112 and the light directing assembly 120, as shown in FIG. By reducing the direct transmission of light from the light source 112 into the microprism 122, the output of the light directing assembly 120 is made more uniform and glare is minimized. The optical element 400 can be made from a rectangular piece of material (eg, plastic, glass or other material) that has approximately the same cross-sectional area at that location in the optical path from the light source 112 to the microprism 122. It has the same flat area. The material may be scattering (diffusely reflective) or partially mirror-like. Illumination assembly 110 encapsulates light source 112 with an optically transmissive material 410 having one or more indices of refraction (n1) instead of simply removing light source 112 suspended in air, as shown in FIG. Further improvements can be made. This optically transmissive material 410 will fill the area surrounding the light source 112 and will be adjacent to the input surface 132 of the microprism 122. This prevents Fresnel reflections at the input surface 132 of the microprism 122 and allows the light source 112 to fill the row of input and input surfaces 132 much more easily than the light source 112. Optically transmissive material 410 is bonded to the input surface by an adhesive layer 412. For optimal movement of the light, these indices are selected such that the refractive index increases as the light travels outward from the light source 112. Thus, the refractive index (n1) of the optically transmissive material 410, the refractive index (n2) of the adhesive layer 412, and the refractive index (n3) value of the light directing assembly 120 are selected such that n1 ≦ n2 ≦ n3. A light element 414 similar to the function for light element 400 in FIG. 29 is disposed on adhesive layer 412. The refractive index of this element 414 should be approximately equal to n2. The transfer of light from the light source 112 to the input surface 132 is also enhanced by introducing the radiation pattern of the light source 112 to the curved surface of the microprism that is supplementing. As shown in FIG. 31, input surface 422 of microprism 420 defines an arc such that the angle of incidence is less than the attenuation angle of microprism 420 farthest from light source 112. This attenuation angle is defined by the following equation: Rs = sin ² (Φi−Φ ′) / sin ² (Φi + Φ ′) Rp = tan ² (Φi−Φ ′) / tan ² (Φi + Φ ′) where n ₁ sinΦi = N ₃ sinΦ 'Rs is the reflectivity of light polarized perpendicular to the plane of incidence, Rp is the reflectivity of light polarized parallel to the plane of incidence, and Φi is the input plane Φ ′ is the angle of the incident light beam traveling through the microprism 420, and Φi and Φ ′ are defined from the normal to the plane of the input surface 422. In FIG. 32, an intermediate light element 430 has been introduced to limit the angular distribution of light entering the light directing assembly 120. Although shown in the drawings as being located between the lighting assembly 110 and the light directing assembly 120, this element 430 can be located in the lighting assembly closest to the light source 112. Further, a second light element 440 similar to light element 400 of FIG. 29 can be provided between light source 112 and intermediate light element 430, thereby reducing the light output of lighting assembly 110. Optical elements 430 and 440 may be formed of plastic, glass or other materials. The index of refraction (n3) of the intermediate light element 430 can be selected to selectively attenuate the larger incident angle rays from the light source 112 and reduce the angular distribution to the light directing assembly 120. For example, when using the above equations to calculate Rs and Rp, increasing the refractive index n ₃ will increase the reflectivity at the incident angle Φi. Assuming that n ₁ is equal to 1, the values of the refractive index n3 are 1.52, 1.7 and 4.0, and the reflectivities at an incident angle of 45 ° are 17.5%, 24% and 65%, respectively. Will. Operation of the lighting device The operation of the device will be described with reference to FIG. In the absence of special structures, the light source 112 emits light in the light directing assembly 120 and similarly in other directions. These rays travel directly to the input surface 132 of the microprism 122 and reflect as required by the above equations for calculating Rs and Rp. The rest of the light is transmitted through the microprism 122 and finally passes through a cooperating lens 142 as indicated by ray A. If light leaving the light source 112 first moves away from the light directing assembly 120, it will encounter the reflector 150. There, the light is reflected toward the light directing assembly 120 and passes through the microprism 122 and the lens 142 as indicated by ray B. Some light rays travel from the light source 112 toward the light directing assembly 120. However, some light rays enter the area 128 adjacent the sidewall 136. If such a ray continues to pass on the path, it will enter the microprism 122 through the side wall 136. However, such rays will not properly exit the light directing assembly 120. Such light rays will in fact distort the light output distribution. Thus, a reflective element is provided in the region 128 so that such irregularly directed light rays can be blocked and redirected. As shown, the light rays leaving the light source 112 reach the solid filler 160. At the solid filler, the light rays are reflected toward reflector 150. There, the light rays are reflected towards the light directing assembly 120 and pass through the light directing assembly 120 as indicated by light rays C. If instead of a reflective material a non-reflective filler is used in the area 128, the light rays will be easily absorbed by the filler. Alternatively, the light is reflected towards a light source. However, this is undesirable because most of such light is absorbed by light source 112. Thus, this reflection mode should be minimized, for example, by using a smaller light source. It should be noted that the present invention is applicable to a wide variety of devices, such as direct lighting devices, including lighting for business, office, residential, outdoor, automotive, and home appliance applications. The present invention also relates to displays for computer, automotive, military, aerospace, consumer, commercial, and industrial applications, and any other device requiring a light source. Applicable. Two examples are the commercial trophy 500 illustrated in FIG. 34 and the downlight 600 illustrated in FIG. The trofer 500 includes two light sources 510, such as T-5 or T-8 fluorescent lamps, a reflector 520, and a light directing assembly 530 comprising a microprism. The downlight 600 also includes a light source 610 (eg, a CFL lamp), a reflector 620, and a light directing assembly 630. Having described what is considered to be the preferred embodiment of the present invention, those skilled in the art will recognize that other and other changes can be made to the embodiment without departing from the spirit of the present invention. Will. It is intended to claim all such embodiments that fall within the scope of the invention. It should be understood that other modifications and combinations are possible, for example, by using the structures disclosed in the cited patents.

────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Kupar, Jerry Wayne             United States New Jersey 08836,             Martinsville, Chulo Road             1336

Claims (1)

[Claims]   1. A lighting device,   (A) a light source;   (B) at least one microprism located very close to the light source Wherein the microprism directs light emitted from a light source. An entrance surface for receiving, an exit surface distal to and parallel to the entrance surface; The incident surface is disposed between the incident surface and the exit surface and is adjacent to the incident surface and the exit surface. Form an obtuse angle with respect to At least one side wall arranged to totally reflect the reflected light beam. A directional assembly,   (C) at least one light blocking means for blocking light from passing through the side wall; When,   Lighting device including.   2. The lighting device according to claim 1,   A lens assembly comprising at least one lens, said micro prism The lighting device further comprising a lens assembly in close proximity to the exit surface of the illumination device.   3. A lighting device,   (A) a light source;   (B) a reflector arranged very close to the light source;   (C) an optical finger disposed in close proximity to the light source and including a plurality of microprisms; A plurality of microprisms, each of the plurality of microprisms being configured to emit light emitted from a light source. And an exit surface that is distal from and parallel to the entrance surface. Disposed between the incident surface and the exit surface and adjacent to the incident surface and the exit surface, Form an obtuse angle with respect to the surface, and Are arranged so as to totally reflect the reflected light, and the gap between the microprisms A light directing assembly including at least one sidewall forming an area;   (D) at least one arranged to block the passage of light through the side wall; Light shielding means,   Lighting device including.   4. The lighting device according to claim 4,   The light directing assembly further includes a bottom wall having two faces, wherein the microprism is The lighting device of claim 1, wherein the exit surface is adjacent to one surface of the bottom wall.   5. The lighting device according to claim 4,   A lens assembly comprising at least one lens, said micro prism The lighting device further comprising a lens assembly in close proximity to the exit surface of the illumination device.   6. The lighting device according to claim 4,   The reflecting device directs the reflected light toward the entrance surface of the microprism. A lighting device that is arranged in such a way that it points.   7. The lighting device according to claim 4,   The light shielding means is a reflection coating provided on a side wall of the micro prism. Reflection lining provided on the side wall of the microprism, The solid filler provided, and the counterpart provided adjacent to the entrance surface of the microprism A mask selected from the group consisting of a radiation mask and a combination thereof. Lighting device.   8. The lighting device according to claim 4,   The lighting assembly reduces light propagation from the light source to the light directing assembly Illumination, further comprising optical means disposed between said light source and said light directing assembly. apparatus.   9. The lighting device according to claim 4,   The lighting assembly limits the angular distribution of light propagated to the light directing assembly Further comprising intermediate optical means disposed between the light source and the light directing assembly. A lighting device.   10. The lighting device according to claim 4,   The incidence surface of the microprism has an angle distribution of light emission from the light source. A lighting device that has a complementary arc shape.